| 摘要 |
PURPOSE:To prevent the backing of a vehicle at the time of parking, etc., on a slope by detecting the operating position of a speed change operating means and delaying the timing of the off-operation of an advancing/backing switchover valve or a parking switchover valve for a defined time later than the on-operation of each switchover valve which takes the place of the off-operation. CONSTITUTION:By providing advancing and backing hydraulic clutches FA, RA and a parking hydraulic brake 83, an advancing/backing switchover valve 71 is operated through the operation to advancing/backing side of a speed change operating means to engage/disengage the advancing and backing hydraulic clutches FA, RA, or a parking switchover valve 75 is operated through the operation to the neutral thereof to operate the parking hydraulic valve 83. And, by detecting the operating position of the speed change operating means through switches 56, 57, the operating solenoids 72, 73 of the advancing/backing switchover valve 71 and the parking switchover valve 75 are controlled by an operating timing controlling means 78, to delay the timing of the off-operation of each switchover valve for a defined time later than the on- operation of each valve which takes the place of the off-operation, thereby, effectively preventing the backing of a vehicle at the time of parking, starting, etc., on a slope.
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